Sunscreening methods



United States Patent 3,414,650 SUNSCREENING METHODS Sigmund C. Catino, Castleton, and Albert F. Strobel, Delmar, N.Y., assignors to GAF Corporation, a corporation of Delaware No Drawing. Filed July 8, 1964, Ser. No. 381,226 8 Claims. (Cl. 42460) ABSTRACT OF THE DISCLOSURE A sunscreening composition and a method of employing the same, said method comprising protecting human skin against the burning rays of actinic radiation by applying to the skin a compound represented by the formula:

C=NN

wherein:

This invention relates to new and useful sunscreen compounds, to compositions containing such compounds, and to methods for protecting the human skin against the burning and degradation effects of sunlight, and in particular to cosmetic compositions incorporating the novel compounds of this invention which are outstandingly useful for protecting the skin against sunlight,

Sunscreening compounds in general have been developed whereby they afford quite satisfactory protection against the burning rays of the sun but which would permit the tanning rays to be transmitted. In the approximate range of from about 2900 to 3100 A. we find the most detrimental burning Wavelengths in the suns rays. The effect of these wavelengths on the human skin is to produce a severe burning, reddening, blistering and edema which is characteristic of many burns. Obviously, this is not only not desirable from an esthetic point of view, but is a severe detriment to human health. In order, therefore, to overcome this effect of the burning rays of the sun, quite satisfactory compounds have been heretofore employed to screen out these burning rays. On the assumption and general acceptance 'by the public that tanning is a desirable phenomenon and is somewhat related to good health, the public has been educated to accept the numerous products currently available to screen out the burning rays of the sun but to permit tanning to occur. Within recent years it has become generally accepted that while tanning may have some beneficial effects especially in that it protects the skin from further burning where there is continued exposure to the sun, nevertheless tanning in and of itself is associated with a general deterioration of the skin due to the effect of the actinic radiation thereon. While the great majority of people are not severely affected by tanning, there are a great number who are so sensitive to even the tanning rays of the sun that exposure to these wavelengths creates serious health hazards. Others have not quite accepted the notion that tanning is beautifying and would prefer to "ice remain untanned. Consequently, for those who must have protection against both burning and tanning rays of the sun, and for those who do not desire to be tanned, there has been a need for a broad spectrum sun-screening composition, which would give adequate protection to the skin, which would be sufficiently stable under conditions of use to remain effective for several hours, which could be readily applied to the skin, and which would not be readily removable such as by simple waterwash. The need for the latter characteristic is evident since it would leave one with a false sense of security if the material were so readily removable as, for example, in bathing.

In order, therefore, to achieve the ends of the present invention it is necessary to provide a composition which has an outstanding filtering action on those rays of the sun from about 2900 A. to about 3500 A.; the range of from about 3200 A. to 3500 A. encompassing the tanning wavelengths present in sunlight.

One of the objects, therefore, of the present invention is to provide outstanding and useful compositions which have excellent filtering action on the ultraviolet rays of solar light and particularly those wavelengths of from about 2900 A. to about 3500 A.

It is still another object of the present invention to provide compositions, and particularly cosmetic compositions, which may be applied to the human skin to protect it against the burning and tanning rays of the sun.

It is a still further object of the present invention to provide processes for preparing the compositions with which the present invention is concerned and further, to provide processes for protecting the human skin against the burning and tanning rays of the sun.

Other objects will appear hereinafter as the description proceeds.

In accordance with the objects of the present invention, it has now been discovered that a class of compounds hereinafter to be described has outstanding screening characteristics for the burning and tanning rays of the sun, and particularly those wavelengths in the ultraviolet region of from about 2900 A. to about 3500 A. and that such compounds have outstanding K values as well as unexpectedly superior light fastness and stability upon exposure to ultraviolet radiation. The K value is a measure of the efficiency of the compound to filter out specified wavelengths of light. A compound with a K value of 1 is one which, at a concentration of 0.1% in a thickness of 1 cm. reduces the light transmitted to 10% of the incident radiation. Thus, a compound with a K=10 at a given wavelength in a concentration of 0.1% will reduce the transmitted radiation to 10% of the incident radiation with a thickness of only 1 mm.

The compounds which are employed in the compositions and processes of this invention have the following general formula:

wherein AR represents a benzene ring devoid of watersolubilizing groups such as sulfonic acid and carboxy and R and R may be hydrogen, alkyl, alkenyl, cycloalkyl, cycloalkenyl and substituted derivatives thereof and at least one of R and R is other than hydrogen. The benzene ring may contain other substituents such as halogen, lower alkyl, (C to C substituted lower alkyls, oxy (such as lower alkoxy, hydroxy lower alkoxy, lower alkoxy, lower alkoxy and the like), and carbalkoxy as well as other nonauxochromic groups which do not have a significant bathochromic effect. By significant we mean a shifting of the absorption of more than about 250 A.

A group which is specifically to be avoided is nitro as well as more than two oxy substituents. It is also preferred that the compounds do not contain an amino group in the aryl moiety since in general such compounds have inferior light fastness although it is to be understood that the effectiveness thereof over the broad spectrum of the burning and tanning wavelengths is on a par with the other compounds.

Suitable substituents for R and R include all of the well known and the general class of alkyls and various substituted forms thereof such as: methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tertiary-butyl, secondarybutyl, n-amyl, iso-amyl, tertiary-amyl and the other isomeric amyls, n-hexyl, iso-hexyl and the other isomeric hexyls, n-heptyl, iso-heptyl and the other isomeric heptyls, n-primary nonyl (nonyl-1), nonyl-(2), nonyl-(3), nonyl- 2-methy1-octyl-2, 4-ethyl-heptyl-4, 2-methyl-4-ethylheXy1-4, n-primary octyl, octyl-(2) (capryl), 2-methyl-3- ethyl-pentyl-3, 2,2,4-trirnethyl-pentyl-4, 2-ethyl-hexyl-1, 3-ethyl-hexyl-3, 2-methyl-heptyl-2, 3-methyl-heptyl-3, 4- methy1-heptyl-4, n-primary decyl (decyl-1), decyl-4 (secondary decyl), 2-ethyl-octyl-3 (tertiary decyl), 4-propylheptyl-4 (tertiary decyl), undecyl-l (n-primary decyl), undecyl-Z (n-secondary decyl), dodecyl-l (n-dodecyl), tridecyl-l (n-tridecyl), tridecyl-7, 3-ethyl-undecyl, tetradecyl-l (n-tetradecyl), pentadecyl-l (n-pentadecyl), pentadecyl-8, hexadecyl (cetyl), heptadecy1-9, octadecyl-l, 2-rnethyl heptadecyl-2, eicosyl-l, docosyl-l, tricosyl-12, tetracosyl, tricapryl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, myrisyl (30 carbons), cyanoethyl, cyano-n-propyl, cyano-isopropyl, cyano-n-butyl, cyanoisobutyl, cyano-n-amyl, cyano-isoamyl, cyanohexyl, cyanoheptyl, cyano-n-octyl, cyano-nonyl, cyanodecyl, cyanolauryl, cyanostearyl and the like, hydroxyethyl, hydroxyn-propyl, hydroxy-isopropyl, hydroxy-n-butyl, hydroxyisobutyl, hydroxy-n-amyl, hydroXy-isoamyl, hydroxyhexyl, hydroxy-heptyl, hydroxy-nonyl, hydroXy-decyl, hydroxy-lauryl, hydroxy-stearyl and the like, carbomethoxyethyl, carbomethoxypropyl, carmomethoXy-butyl, carbomethoxyamyl, carbomethoxyhexyl, carbethoxyethyl, carbethoxypropyl, carbethoxybutyl, etc., carbopropoxyethyl, carbopropoxypropyl, carbopropoxybutyl, etc., carbobutoxyethyl, carbobutoxybutyl, etc., chloroethyl, chloropropyl (N-propyl, isopropyl), chlorobutyl (N-butyl, isobutyl, etc.), chloroamyl, chlorohexyl, chlorodecyl, chlorolauryl, and the like, bromoethyl, bromopropyl (N-propyl, isopropyl), bromobutyl (N-butyl, isobutyl, etc.), bromoamyl, bromohexyl, bromodecyl, bromolauryl, and the like, methoxyethyl, methoxypropyl (N-propyl, isopropyl), methoxybutyl (N-butyl, isobutyl, etc.), methoxyamyl, methoxyhexyl, methoxydecyl, methoxylauryl, and the like, ethoxyethyl, ethoxypropyl (N-propy-l, isopropyl), ethoxybutyl (N-butyl, isobutyl, etc.) ethoxyamyl, ethoxyhexyl, ethoxydecyl, ethoxylauryl, and the like, hydroxyethoxyethyl, hydroxyethoxypropyl, hydroxyethoxybutyl, hydroxyethoxyamyl, hydroxypropoxyethyl, hydroxypropoxypropyl, hydroxypropoxybutyl, hydroxypropoxyamyl, hydroxybutoxyethyl, hydroxybutoxypropyl, hyroxybutoxybutyl, hydroxy-butoxyamyl, allyl, methallyl, crotyl, butenyl-l, pentenyl-l, 'y-isopropyl allyl, 2-methyl-octenyl-6 and the like, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclopentenyl (-2), cyclopentenyl (-3), cyclopentenyl (-4), cyclohexenyl (-2), cyclohexenyl (-3), cyclohexenyl (-4), cyclohexenyl (-5), Z-methyl cyclohexenyl (-4-), 4- chlorocyclohexyl, 4-allyl cyclohexyl, 3-bromocyclohexyl, 2-isopropyl cyclohexyl, 3-n-propy1 cyclohexyl, 4(2-chloroethyl) cyclohexyl, 4(2-hydroxyethyl) cyclohexyl, 4- hydroxycyclohexyl, 3-methyl-4-chlorocyclohexyl, 3,4-dibromocyclohexyl, 2,4-dirnethylcyclohexyl.

Similar substituents may be present in the benzene ring with the proviso as pointed out above that it is preferred that the carbon chain be no greater than about 8 carbon atoms. Also, as mentioned above, the benzene ring may contain halogen substituents such as chlorine, bromine,

iodine and fluorine as well as alkyl sulfonyls such as methyl isulfonyl, ethyl sulfonyl, carboxamido, N-methylcarboxamide, N-ethylcarboxamide, N,N-dimethylcarboxamide, N.N-diethylcarboxamide, sulfonamido, etc.

The general procedure for preparing the compound of this invention involves a condensation of a benzaldehyde with an N-alkylatedor N,N-dialkylated hydrazine (or the substituted alkylated forms thereof). The condensation may be carried out in any suitable manner, i.e., with or without solvent or diluent, although a solvent is preferred. The methine compounds form readily upon refluxing and removal of water formed during the condensation reaction. Among suitable aldehydes which may be employed as reactants in preparing the compounds of this invention are:

benzaldehyde o-tolualdehyde m-tolualdehyde p-tolualdehyde p-ethyl benzaldehyde 2,4-dimethyl benzaldehyde 2,5-dimethyl benzaldehyde 3,4-dimethy1 benzaldehyde p-isopropyl benzaldehyde 2,4,6-trimethyl benzaldehyde 2,4,5-trimethyl benzaldehyde 2-chloro benzaldehyde 3-chloro benzaldehyde 4-chloro benzaldehyde Z-bromo benzaldehyde 3-brorno benzaldehyde 4-brorno benzaldehyde 2,4-dichloro benzaldehyde 2,5-dichloro benzaldehyde 2,6-dichloro benzaldehyde 3,4-dich1oro benzaldehyde 2,3,4-trichloro benzaldehyde 2,3,6-trichloro benzaldehyde 2,4,5-trichloro benzaldehyde 2,4,6-trichloro benzaldehyde 2,3,4,6-tetrachloro benzaldehyde pentachloro benzaldehyde 2,4,6-tribromo benzaldehyde 2,3,4,S-tetrabromo benzaldehyde 2-fiuorobenzaldehyde 2-bromo-6-chloro benzaldehyde 2-iodo-benzaldehyde 3-iodo-benzaldehyde 4-iodo-benzaldehyde 4-chloro-3,5-dibromo benzaldehyde 4-chloro-3-bromo benzaldehyde 3-chloro-4-bromo benzaldehyde 4-chloro-3-iodo benzaldehyde 2,4-dichloro-3,5-dibromo benzaldehyde 4-chloro-2-methyl benzaldehyde 4,6-dic-hloro-3-methyl benzaldehyde 2-iodo-3-methyl benzaldehyde 6-chloro-2,4-dimethyl benzaldehyde 5-chloro-2,4-dimethyl benzaldehyde 3,5dichloro-2,4-dimethyl benzaldehyde 4-bromo-2,5-dimethyl benzaldehyde 2-allyl-4-allyloxy benzaldehyde 3-allyl-4-allyloxy benzaldehyde 3-aly-2-(2-choroethoxy) benzaldehyde 3-allyl-2-(3-chloro-2-hydroxypropoxy) benzaldehyde 3-allyl-4-hydroxy benzaldehyde m-allyloxy benzaldehyde o-allyloxy benzaldehyde p-allyloxy benzaldehyde o-benzyloxy benzaldehyde m-benzyloxy benzaldehyde p-benzyloxy benzaldehyde 4-benzyloXy-3-bromo benzaldehyde Z-benzyloxy-S-chloro benzaldehyde 4-benzy10xy-3-chloro henzaldehyde 4-benzyloxy-3,5-dibromo benzaldehyde 4-benzyloxy-3-iodo benzaldehyde 4-bromo-3-hydroxy benzaldehyde Z-bromo-S-ethoxy benzaldehyde 3-bromo-4-hydroxy benzaldehyde o-butoxy benzaldehyde m-butoxy benzaldehyde p-butoxy benzaldehyde p-(Z-butenyloxy) benzaldehyde p-sec. butyl benzaldehyde p-tert. butyl benzaldehyde 2-butyl-4,6-dimethyl benzaldehyde 3-tert. butyl-4-ethoxy benzaldehyde p-butylsulfonyl benzaldehyde 6-tert. butyl-2,3,4-trimethyl benzaldehyde o-(o-chlorobenzyloxy) benzaldehyde m-(o-chlorobenzyloxy) benzaldehyde p-(o-chlorobenzyloxy) benzaldehyde o-(p-chlorobenzyloxy) benzaldehyde m- (p-chlorobenzyloxy) benzaldehyde p-(p-chlorobenzyloxy) benzaldehyde o-(2-chloroethoxy) benzaldehyde p-(2-chloroethoxy) benzaldehyde 2-chloro-3-hydroxy benzaldehyde 2-chloro-5-hydroxy benzaldehyde 2-chloro-4-hydroxy benzaldehyde 3-chloro-4-hydroxy benzaldehyde p [2- (2-butoxyethoxy) ethoxy] henzaldehyde 3-chloro-4-hydroxy benzaldehyde 4-chloro-3-hydroxy benzaldehyde o- 3-chloro-2-hydroxypropoxy) benzaldehyde p-(3-chloro-2-hydroxypropoxy) benzaldehyde o-(2-cyanoethoxy) benzaldehyde p-hydroxy benzaldehyde m-hydroxy benzaldehyde p-methoxy benzaldehyde m-methoxy benzaldehyde 4-sulfamy1 benzaldehyde 6-ch1oro-4-su1famyl benzaldehyde p-formyl-N,N-bis(Z-hydroxyethyl) benzene sulfonamide p-formyl-N-methyl benzenesulfonamide p-formyl-N-ethyl benzenesulfonamide p-formyl-N-octyl benzenesulfonarnide p-for-myl-N-phenethyl =benzenesulfonamide p-forrnyl-N,N-dimethyl benzenesulfonamide p-formyl-N,N-diethyl benzenesulfonamide p-formyl-N,N-dipr0pyl benzenesulfonamide p-forrnyl-N,N-dioctyl benzenesulfonamide 3-formyl benzamide 4-formyl benzamide 2,6-dichloro-3-formyl benzamide 2,4-dichloro-3-formy1 benzamide 2,4,6-trichloro-3-formyl benzamide 4,5,6-trich1oro-3-formyl benzamide 2,5-dichloro-4-formyl benzamide 2,3,5-trichloro-4-formyl benzamide 2,3,6-trichloro-4-formyl benzamide Z-carbomethoxy benzaldehyde 3-carbomethoxy benzaldehyde 4-carbomethoxy benzaldehyde 2-carboethoxy benzaldehyde 3-carboethoxy benzaldehyde 4-carboethoxy benzaldehyde 2-carboisopropoxy benzaldehyde S-carboisopropoxy benzaldehyde 4-carboisopropoxy benzaldehyde 4-carbo (n) butoxy benzaldehyde o-methoxy benzaldehyde o-n-propoxy benzaldehyde p-n-propoxy benzaldehyde p-isopropoxy benzaldehyde p-cyclohexyl benzaldehyde p-cyclohexyloxy benzaldehyde p-cyclopentyl 'benzaldehyde Examples of specific hydrazines are:

methyl hydrazine ethyl hydrazine n-propyl hydrazine isopropyl hydrazine n-butyl hydrazine n-pentyl hydrazine n-heXyl hydrazine iso octyl hydrazine undecyl hydrazine stearyl hydrazine sec.-n-octyl hydrazine dodecyl hydrazine hydrazine acetic acid hydrazine acetic acid methyl ester hydrazine acetic acid ethyl ester hydrazine acetic acid isobutyl ester hydrazine acetic acid iso octyl ester hydrazine acetic acid hexadecyl ester fi-hydroxyethyl hydrazine p-hydroxypropyl hydrazine a-hydrazine propionic acid a-hydrazine propionic acid methyl ester a-hydrazine propionic acid ethyl ester a-hydrazine propionic acid n-propyl ester a-hydrazine propionic acid iso octyl ester tat-hydrazine hexanoic acid ethyl ester hydrazine acetic acid, hydroxyethyl ester hydrazine acetic acid, methoxy ethyl ester hydrazine acetamide hydrazine N-methyl acetamide hydrazine N-hydroxyethyl acetamide (NI-I NHCH CONH -CH CH OH) hydrazine, N, N-bis(hydroxyethyl) acetamide N,N-dirnethyl hydrazine N,N-diethyl hydrazine N-methyl-N'ethyl hydrazine N-methyl-N-butyl hydrazine Nmethy1-N-isobutyl hydrazine N,N-di-n-propyl hydrazine N,N-dibenzyl hydrazine N,N-diisobutyl hydrazine N,N-dipentyl hydrazine N,N-dicyclohexyl hydrazine allyl hydrazine N,N-diallyl hydrazine cyclopentyl hydrazine cyclohexyl hydrazine 4-chl0rocyclohexyl hydrazine 4-(2-chloroethyl) cyclohexyl hydrazine pentenyl(-1) hydrazine crotyl hydrazine 4-hydroxycyclohexyl hydrazine -hydrazino propyleneglycol (CH OHCHOHCH NHNH N,N-bis (B-hydroxyethyl) hydrazine B-chloroethyl hydrazine ,B-cyanoethyl hydrazine fi-methoxyethyl hydrazine 'y-chloropropyl hydrazine ,B-chloropropyl hydrazine fl-hydroxyethoxyethyl hydrazine carbethoxyethyl hydrazine In the following examples which will serve to illustrate the present invention, parts are by weight unless otherwise indicated.

Example 1 To ml. of anhydrous ethanol in a 500 m1. flask are added 70.3 g. of p-chlorobenzaldehyde (0.5 M.) and 30 g. of N,N-dimethyl hydrazine (0.5 M.). The contents are refluxed for 1 hour, then diluted with 250 ml. of ethanol and cooled to 50 C. A copious formation of crystals occurs. This is filtered to yield 62 g. of product of the formula:

Oil; Q Cl OH=NN with a M.P. of 6869.6 C. and at K at 302m =1l2.

Example 2 Example 1 is repeated except that the aldehyde is replaced by 0.5 M. of the following aldehydes:

A. p-hydroxy benzaldehyde B. p-methoxy benzaldehyde C. p-methyl benzaldehyde The products 2A, 2B and 2C have the following characteristics:

Product M.P. C.)

.. 156.2-158 B.P. 120 C. at 0.6 mm B.P. 07 C. at 0.75 mm 122.8 at 292 m 116.4 at 292 my. 109.7 at 295 m Example 3 Example 1 is again repeated employing the following aldehydes (0.5 m.) in place of the aldehyde of Example 1:

Example 4 The compounds of Examples 1 and 2 are made up separately as 5% solutions by weight in coconut oil. The solutions are applied, separately, to the skin and exposed to summer sunlight for four hours beginning at midday. The compounds give complete protection against burning with but slight tanning taking place. These compounds are particularly outstanding in their light fastness which permits their use and exposure for lengthy periods of time with assurance of adequate protection.

Example 5 The procedure of Example 1 is repeated employing 0.5 m. of the following hydrazines in place of the 0.5 m. of N,N-dimethyl hydrazine of Example 1:

. methyl hydrazine n-hexyl hydrazine hydrazine acetic acid stearyl hydrazine hydrazine acetic acid isooctyl ester fi-hydroxypropyl hydrazine hydrazine acetamide hydrazine N-methyl acetamide I. N-rnethyl-N-ethyl hydrazine J. N,N-dihexyl hydrazine K. N,N-dicyclohexyl hydrazine L. N,N-diallyl hydrazine M. 4-chlorocyclohexyl hydrazine pentenyl-l-hydrazine l-cyclopentenyll-hydrazine fl-chloroethyl hydrazine fi-cyanoethyl hydrazine B-methoxyethyl hydrazine fl-hydroxyethoxyethyl hydrazine carbethoxyethyl hydrazine N-B-chloroethyl-N-ethyl hydrazine N-B-hydroxyethyl-N-carboxymethyl hydrazine Example 6 Example 4 is repeated using the indicated amounts of absorber (by weight) and solvent:

A. 1% in coconut oil B. 1% in cottonseed oil C. 1% in medicinal mineral oil D. 10% in coconut oil In place of solutions, it is, of course, clear that the compounds described herein may be used in emulsion systems, in powders and applied in 100% active form, particularly when the absorber is a liquid. The following illustrate such formulations.

Example 7 A mixture of 6 parts mineral oil and 7 parts stearic acid is heated to C. and add, with stirring, to a heated (75 C.) mixture of 70 parts water, 3 parts glycerin and 2.5 parts triethanolamine, 2 parts sodium alginate. To the resultant emulsion, there is added, while hot (65 C.) 2.5 parts of the compound of Example 1 dissolved in 7.0 parts coconut oil. An excellent, smooth lotion results.

Example 8 The compounds of Examples 1 and 2 are incorporated, separately, into a cosmetic cream at 2% (by weight) concentration. The cream is composed of:

Parts Petrolatum 9 Mineral oil 4 Water 62 Glyceryl monostearate 6 Beeswax 3.5 Polyvinylpyrrolidone (K=30) 2.0

Example 9 The aldehydes employed in Examples 3A, 3C, 3E, 3H, 31, 3K, 3R, and 38 are condensed with methyl hydrazine following the procedure and amounts used in Example 1.

Example 10 The aldehydes used in Examples 3A, 3D, 3F, 3H, 3], 3P, 3R and 3T are condensed with hydrazine acetic acid isooctyl ester as in Example 1.

In the above examples there have been illustrated the preparation of numerous compounds coming within the scope of the present invention as well as exemplifications of the use of many of such compounds as ultra-violet absorbers, and particularly as sun-screen agents. As described, the oil-soluble compounds may be applied to the skin as solutions in suitable solvent oils, or as dispersions in conventional aqueous media, or in emulsions of both the oil-in-water and water-in-oil types. Illustrations have been given showing the use of various additives which are conventional in such cosmetic preparations which are to be applied to the skin, and it is to be understood that any other conventional additives normally used for topical applications may be incorporated in the compositions containing the absorbers herein described. Again as illustrated, various concentrations from 1 to 10% of absorber have been shown but again, such concentrations are not critical. For most applications and from practical considerations based upon the efficacy of these sun-screen agents and economics of the resultant composition, amounts of from about 0.1% by weight to about 10% by weight may be used, and most preferably from about 0.5% to about 5% by weight based on the weight of the total composition to be topically applied. As*previously mentioned, the compounds may be employed in their 100% active form where so desired, especially in those instances where the agents are liquids. Since the absorption characteristics of the various compounds herein disclosed vary and are obviously not all identical, it may be desired to employ mixtures of two or more compounds in order to obtain specifically attainable absorption performance. Still further, other well known absorbers may also be used in combination with those herein described.

Other variations in and modifications of the described processes which will be obvious to those skilled in the art can be made in this invention without departing from the scope or spirit thereof.

We claim:

1. A method for protecting human skin against the burning rays of actinic radiation, which comprises applying to the skin an effective amount of a compound represented by the formula:

wherein:

(A) X is a substituent selected from the group consisting of lower alkyl, halogen, hydroxy, lower alkoxy, lower alkoxy lower alkoxy, hydroxy lower alkoxy, methyl sulfonyl, ethyl sulfonyl, butyl sulfonyl, carboxamido, sulfonamido and carbalkoxy of up to 8 carbon atoms;

(-B) n is an integer from to except when X is oxy n is an integer from 1 to 2, and

-(C) R and R are independently selected from the group consisting of hydrogen, alkyl, alkenyl of up to 8 carbon atoms, cycloalkyl of up to 8 carbon atoms, and cycloalkenyl of up to 8 carbon atoms, and at least one of R and R is other than hydrogen.

10 1k2.1Th method of claim 1 wherein both R and R are 3. The method of claim 2 wherein both R and R are methyl.

4. The method of claim 1 wherein one of R and R is alkyl, the other being hydrogen.

5. The method of claim 1 wherein said compound corresponds to the formula:

6. The method of claim 1 wherein said compound corresponds to the formula:

7. The method of claim 6 wherein the N-alkyl substituents are methyl.

8. The method of claim 7 wherein said compound corresponds to the formula:

CHI

References Cited UNITED STATES PATENTS OTHER REFERENCES Chemical Abstracts, vol. 43:6591-93 (1949).

ALBERT T. MEYERS, Primary Examiner.

V. C. CLARKE, Assistant Examiner. 

